The nine airlines that operate direct flights to the U.S. from those airports are Egyptair, Emirates Airline, Etihad Airways, Kuwait Airways, Qatar Airways, Royal Air Maroc, Royal Jordanian Airlines, Saudi Arabian Airlines and Turkish Airlines.

U.S. airlines are not affected because none of them fly from the airports in question to the U.S., according to U.S. government officials.

Passengers will still be allowed to take electronic devices onto flights departing from the U.S.

Which devices are banned?

Passengers will have to check in any electronic devices bigger than a smartphone. That includes laptops, cameras, gaming devices and tablets such as iPads.

Medical devices required during the flight will still be allowed in the cabin after security screening.

When will it take effect?

The U.S. government officially notified the airlines at 3 a.m. ET Tuesday. They have 96 hours to fully comply.

And if they don't? "We will work with the FAA to pull their certificate and they will not be allowed to fly to the United States," one senior U.S. official said.

What are the airlines saying?

Turkish Airlines has told its passengers traveling to the U.S. that anything bigger than a smartphone must be checked into the baggage hold.

Etihad said it had received the notification from the U.S. government and was reviewing it. A spokeswoman for Qatar Airways said it would take full advantage of the 96-hour notice period and implement change on Friday.

Emirates said it hadn't yet received any notification but would "comply with any new operational or regulatory requirements issued by the relevant authorities."

Other airlines, including Royal Jordanian and Saudi Arabian Airlines, have said they will implement the measures.

What's the reason for the ban?

U.S. officials say the move is a response to fears that terrorist groups may target passenger planes by smuggling explosive devices in consumer goods.

One official said there's no specific plot authorities are aware of, but the U.S. has been considering such a ban for some time.

Why these airports?

The U.S. is especially concerned about the 10 airports in question, the official said, because of screening issues and the possibility of terrorists infiltrating authorized airport personnel.

Flight and cabin crews are not covered by the new restrictions.

Officials said that they believe a threat to the U.S. would be negated if a passenger transferred through a secondary city with additional and more trustworthy screening procedures.

Isn't it dangerous to put electronic devices in checked baggage?

Safety experts and regulators have long warned that batteries shipped in bulk could constitute a fire risk that ultimately could bring down an aircraft. The International Civil Aviation Organization advised global regulators last year to ban carrying bulk shipments of such batteries in the cargo holds of passenger jets.

But electronics spread out across a person's luggage pose far less of a threat than palettes of lithium batteries, according to a U.S. aviation official.

-- Rene Marsh, Isil Sariyuce in Istanbul and John Defterios in Abu Dhabi contributed to this report.